Fuel injection diaphragm mechanism



May 3l, 1960 s. H. MICK Erm. 2,938,545

FUEL INJECTION DIAPHRAGM MECHANISM Filed May 15, 1957 Arron-wax United States Patent O FUEL INJECTION DIAPHRAGM MECHANISM Stanley H. Mick, St. Clair Shores, and John Zimmerman, Grosse Pointe Woods, Mich., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed May 15, 1957, Ser. No. 659,409

4 Claims. (Cl. 137-784) The present device relates to an improved diaphragmlinkage mechanism for a fuel injection system of the type shown in copending application Serial No. 608,853 Dolza, led September 10, 1956, now Patent No. 2,843,098. More particularly, the present invention is devoted to an improved and simplified mechanism for connecting the vacuum diaphragm to the metering valve control linkage in a way which reduces the frictional and mass inertia thereof.

In previous devices used in connecting the diaphragm and control linkage it has been necessary to employ special tools in assembling the control linkage to the diaphragm whereas the present device permits connection without the use of tools.

Heretofore the linkage was connected to the diaphragm in a way resulting in rubbing or friction between the linkage and the supporting structure and introducing unnecessary inertia into the fuel control system. In the present device the linkage and diaphragm connecting structure is uniquely constructed to provide means for centering or positioning the linkage in such a way as to be free of frictional engagement with the supporting structure during operation of the system.

The details of the ,present invention as well as other objects and advantages are set forth in the detailed description which follows.

ln the drawing:

Figure 1 is a partially sectioned view of a portion of a fuel injection system embodying the subject invention; and

Figure 2 is an enlarged sectional view showing the invention in greater detail.

The fuel injection system, per se, forms no part of the present invention and reference is made to the aforenoted patent for a description thereof. Only that part of the fuel injection system will be described as is necessary to provide the proper environment for the subject invention.

IA metering system casing is shown at and includes a slidable metering valve 12 disposed therein. An upper wall `14 of casing 10 is suitably recessed at 16 to support a exible diaphragm 18 thereover and which diaphragm is peripherally clamped to wall 14 by a cover member 20. A chamber 22 formed by the cover 20 and diaphragm 18 is adapted to be communicated with a vacuum force proportional to mass air iiow through the system which in part determines the position of the metering valve 12.

Upper wall 14 lis perforated at 23 to permit a rod element 24 of the metering valve control linkage to project therethrough and be connected to the diaphragm 18. The other end of the rod 24 is connected to a lever 26 which is supported intermediate its ends upon an adjustable fulcrum member 28. The other end of lever 26 is adapted to bias against the metering valve 12. Thus as the vacuum force in chamber 22 increases the diaphragm 18 will move upwardly carrying rod 24 therewith and causing lever 26 to pivot about adjustable fulcrum 28 in a eounterclockwise direction moving the metering valve 12 in a flow increasing direction. As thus far described the mechanism is the same as in the aforenoted patent.

In the earlier Dolza patent the means whereby the rod 24 was connected to the diaphragm 18 as well as the rod itself constituted a relatively large mass when compared with the vacuum control forces available in chamber 22. In the present device, a flanged anchor hub or sleeve 30 is ixed to the diaphragm 18 as by staking the ange 31 to the diaphragm reinforcing plate 32. The anchor hub 30 is internally threaded and includes a chamfered end portion 34. The end 36 of rod 24 is adapted to be threaded within the hub 30 combining the connecting and locking functions in a single element. I

The opening 23 in the upper casing wall 14 has a'seal or seat 38 xed therewithin and includes an opening 40 therein. The opening 40 in seal 38 is large enough to permit the passage therethrough of the threaded end 36 of rod 24. 'Ihe seal 38 includes a chamfered portion 42 extending from opening 40 to the upper seal surface 43. Chamfer 42 corresponds to the chamfered' end 34`of anchor hub 30. l f

The lower end of rod 24 is iiattened at 44 for convenient articulation to the lever 26.

The hole 40 is made as small as possible around rod 24 to prevent oat bowl pressures from acting on the underside of the diaphragm which is vented to the venturi inlet. The small clearance between the hole 40 and rod 24 is the reason for the exact centering requirement.

In assembling the diaphragm 18 to the metering control valve linkage the rod 24 is connected to lever 26, thereafter, the upper end of rod 24 is passed upwardly through the opening 40 in seal 38 and threaded to a suitable extent within anchor hub 30. The diaphragm 18 is depressed below its normal position such that the anchor chamfer 34 is seated upon 'the seal chamfer 42, as shown in Figure 2. In this way the rod 24 is centered with respect to the seal opening 40. With the parts in this position cover 20 is fastened to wall 14 clamping the diaphragm 18 in a position compatible with the centered rod 24. In thus concentrically positioning the rod 24 with respect to the seal 38 the rod will not rub against the seal during operation of the diaphragm.

The old method of attachment required indexing the diaphragm to line up the hold down screws of cover 2t). This indexing had to be done before the rod was tightened to the diaphragm and had to be maintained during the tightening operation. The new method allows the diaphragm to rotate after assembly to the rod to permit lining up the holes. j

The avoiding of frictional contact between lthe rod 24 and the seal 38 has reduced the hysteresis previously introduced into the control function in the earlier device by reducing both the mass and friction inertia in the system. The result of this construction is a more accurate control of the metering valve 12 as well as a cheaper more easily assembled unit.

We claim:

l. A metering control mechanism for a fuel injection system comprising a casing, a exible diaphragm peripherally supported within said casing, an opening in said casing coaxially aligned with a similar opening in said diaphragm, a seal member xed in said-casing opening and including a central opening therethrough, said seal including a chamfered shoulder extending from one end of said opening, an element having 'a -threaded opening extending axially therethrough, said element being mounted in and projecting through the opening in said diaphragm, said element including a chamfered end adapted to coact with said chamfered seal shoulder to coaxially align said element and seal openings, and an elongated rod including an end threaded within the ele- -mentfope'ning and to support said rod extending through Ysaid seal opening in radially spaced relation to said seal opening.

2. A metering control mechanism for a fuel injection system comprising va casing, a flexible'diaphragm peripherally supported within said casing, an opening Iin saidasing coaxially aligned witha similar opening in saiddiaphragm,Y a seal member xed in s'aid casing 4opening and includinga central opening therethrough, jsaid f Aseal including a hamfered shoulder extending 'from 'one -end of said opening and'terminating in the lseal surface proximate thediaphra gm, -an element having a threaded opening extending 'axially therethrough ,said "element -being mounted in andlprojecting'through,the'openingfin ferally supported-within said casing, va reinforcing plate mounted centrally of said diaphragm for movement there- .wi-th, an Vopening-in said casing coaxially aligned with similar openings in said diaphragm and reinforcing plate,

a seal member xed vinV said 'casing openingad including a central opening therethrough,4 said seal including a chamfered shoulder vextending from one end of said opening and terminating in the s'eal surface proximate the diaphragm, a sleeve element having a threaded opening extending axially therethrough, said element being mounted in and projecting 'through the opening in said diaphragm, va flange formed on. said .sleevevtforvxedly supporting the sleeve Within the plate opening, said 'element including a chamfered zend adaptedto .coact with said charnferedseal `shoulder to ycoaJrially aligntsaid ele- .mentrand seal openings, ,andan elongated rod including an end threaded within the element opening t`ofsupport said rod in radially spaced relation tosaidLseal.

4. A metering control mechanismas defined in claim 3 in which the-.'angean'd:chamferedl end of said sleeve element are disposed on opposite sides of said diaphragm.

.'eferenceslCit'ed' -in the lleiof this patent V`UNITED STATESPPATENTS Y 31355596 Stover Y..'Apr.;2.6,1932 Y'2,651g31j6 'Fageoi sepas, '1953 2,704,548 .Ralston ",Mar. 22, .1955

y2,717,792 iPeuey 1sept.. 13, 1955 

